Poly-N-acetyl glucosamine (PNAG) is a 0-1-6 linked surface polysaccharide that is expressed by a broad range of bacterial pathogens, including Staphylococcus aureus, Escherichia coli, and Yersinia pestis. It has high potential to be a widely protective vaccine against a diverse array of pathogens, but specific glycoforms, notably ones lacking acetate substituents on the amino groups of the glucosamine monosaccharide are needed to produce optimal immunity. Additionally, active and passive vaccination strategies targeting PNAG have moved into early clinical development, but the utility of this antigen as a single component vaccine is likely to be suboptimal, Furthermore, pathogen-derived PNAG antigen may be suboptimal for synthesizing vaccines that elicit the most effective protective antibody response. Finally, producing conjugate vaccines using an array of different carrier proteins can be time consuming and expensive. To address these issues, synthetic oligoglucosamine glycoforms will be produced that can be easily stored and readily conjugated to a variety of recombinant carrier proteins derived from targeted pathogens. These vaccines will be evaluated for engendering protection against methicillin-resistant S. aureus (MRSA), enterohemorrhagic E. coli (EHEC) O157 and similar Shiga toxin (STX)-prpducing strains, and Y. pestis. Moreover, these PNAG-based vaccines will also be evaluated for the ability to prevent mucpsal colonization as well as pneumonia, two critical interventions that have not yet been tested. PNAG-based conjugate vaccines will be paired with recombinant proteins specific to each of the pathogens to determine if additive, synergistic or possibly even inhibitory immune effects can be engendered by multicomponent preparations. Conjugate vaccines for MRSA will contain synthetic PNAG oligosaccharides plus capsular polysaccharide types 5 (CP5) and 8 (CP8). Carrier protein antigens will include those that contribute to protective immunity, such as alpha-hemolysin toxoid (Hla) or clumping factor B (ClfB). Vaccines for EHEC will include conjugates of synthetic PNAG oligosaccharides and STX. Synthetic PNAG oligoglucosamines conjugated to LcrV, F1 capsule or a fusion protein of these will be used to target Y. pestis. We will investigate the type of immune effectors generated by immunization and evaluate their functionality for the prevention of mucosal colonization and infection by these pathogenic bacteria.